This book, originally published in 1975, presents a theory of behaviour in coalitions and presents an application of the theory to Indian political party coalitions. The major findings of the study are (a) the size of political parties is unimportant when important benefits are distributed in coalitions; (b) behaviour that combines a moderate degree of cooperation and competition with one’s allies leads to a much greater political success than either highly competitive or highly cooperative behaviour; and © political parties with leaders whose personalities can be characterised as having a high need to achieve enjoy much greater electoral success than parties whose leaders are relatively low in need for achievement. The book is important because the theory is able to explain long term and short term consequences of coalitions; it presents a careful analysis of political party behaviour in India and it combines elements of positive political theory, empirical political science and psychology in explaining coalition behaviour.